Microwave Photonic Signal Processing Technology: Mixer And Phase Shifter

Microwave photonics is a burgeoning subject starting from the end of the last century.It combines the advantages of microwave technology and optical technology such as overcoming the inherent electronic limitations,realize high sapling rate,high time-bandwidth product capability,low loss,immunity to electromagnetic interference and compatible with an optical fiber systems.In this thesis,several microwave photonic signal processors about downconversion or phase shift was presented,and mainly consisted of the following contents:?1?This paper presents a new technique for realizing continuous 0°-360° RF signal phase shift over a very wide bandwidth.It is based on using single-sideband modulation together with optical filtering to largely suppress one of the RF modulation sidebands over a wide input RF frequency range,and controlling the phase of the optical carrier to shift an RF signal phase.Experimental results demonstrate only ±1d B amplitude variation and ±5° phase de-viation from the desired RF signal phase shift over 2–40GHz bandwidth and the RF signal amplitude control function.The phase shifter wavelength insensitive performance is also demonstrated experimentally.?2?A new photonic microwave image rejection mixer that can achieve high conversion efficiency and have a wide bandwidth is presented.It is based on an integrated dual-parallel Mach Zehnder modulator with a 90° polarization rotator on one branch of the modulator.Experimental results demonstrate frequency downconversion with an image rejection function,a high conversion efficiency of >-5d B and a high image rejection ratio > 50 d B over a wide 3 to 20 GHz frequency range.?3?A microwave photonic signal processor that is capable of simultaneously realizing sub harmonic frequency down conversion and IF signal phase shifting operation is presented.The IF signal generated by the frequency down conversion process is obtained by the beating of the 2^nd order LO sideband with the fundamental RFsignal sideband at the photodetector.The phase of the IF signal can be tuned continuously from 0° to 360° by controlling a single DC voltage.The signal processor can be designed to have a very wide bandwidth as it only involves optical components.Experimental results are presented that demonstrate frequency down conversion with > 8.8d B conversion efficiency over 6 to 40 GHz RF signal bandwidth and 0.05 to 10 GHz IF signal bandwidth,and a continuous 0° to 360° phase shift on the output IF signal.